* Oleg Nesterov <o...@redhat.com> [2012-11-24 19:02:33]:
> Simply remove UPROBE_RUN_HANDLER and the corresponding code.
>
> It can only help if uprobe has a single consumer, and in fact
> it is no longer needed after handler_chain() was changed to use
> ->register_rwsem, we simply can not race with uprobe_register().
>
> Signed-off-by: Oleg Nesterov <o...@redhat.com>
Acked-by: Srikar Dronamraju <sri...@linux.vnet.ibm.com>
> ---
> kernel/events/uprobes.c | 23 +++++------------------
> 1 files changed, 5 insertions(+), 18 deletions(-)
>
> diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
> index 873c993..97c3874 100644
> --- a/kernel/events/uprobes.c
> +++ b/kernel/events/uprobes.c
> @@ -83,10 +83,8 @@ static atomic_t uprobe_events = ATOMIC_INIT(0);
>
> /* Have a copy of original instruction */
> #define UPROBE_COPY_INSN 0
> -/* Dont run handlers when first register/ last unregister in progress*/
> -#define UPROBE_RUN_HANDLER 1
> /* Can skip singlestep */
> -#define UPROBE_SKIP_SSTEP 2
> +#define UPROBE_SKIP_SSTEP 1
>
> struct uprobe {
> struct rb_node rb_node; /* node in the rb tree */
> @@ -475,9 +473,6 @@ static void handler_chain(struct uprobe *uprobe, struct
> pt_regs *regs)
> {
> struct uprobe_consumer *uc;
>
> - if (!test_bit(UPROBE_RUN_HANDLER, &uprobe->flags))
> - return;
> -
> down_read(&uprobe->register_rwsem);
> for (uc = uprobe->consumers; uc; uc = uc->next)
> uc->handler(uc, regs);
> @@ -825,13 +820,8 @@ static int register_for_each_vma(struct uprobe *uprobe,
> bool is_register)
>
> static int __uprobe_register(struct uprobe *uprobe, struct uprobe_consumer
> *uc)
> {
> - int err;
> -
> consumer_add(uprobe, uc);
> - err = register_for_each_vma(uprobe, true);
> - if (!err) /* TODO: pointless unless the first consumer */
> - set_bit(UPROBE_RUN_HANDLER, &uprobe->flags);
> - return err;
> + return register_for_each_vma(uprobe, true);
> }
>
> static void __uprobe_unregister(struct uprobe *uprobe, struct
> uprobe_consumer *uc)
> @@ -842,12 +832,9 @@ static void __uprobe_unregister(struct uprobe *uprobe,
> struct uprobe_consumer *u
> return;
>
> err = register_for_each_vma(uprobe, false);
> - if (!uprobe->consumers) {
> - clear_bit(UPROBE_RUN_HANDLER, &uprobe->flags);
> - /* TODO : cant unregister? schedule a worker thread */
> - if (!err)
> - delete_uprobe(uprobe);
> - }
> + /* TODO : cant unregister? schedule a worker thread */
> + if (!uprobe->consumers && !err)
> + delete_uprobe(uprobe);
> }
>
> /*
> --
> 1.5.5.1
>
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